Agrilus difficilis

Distinguished from similar honey locust-associated Agrilus species (A. egeniformis, A. fallax, A. pseudofallax) by its relatively large size, coppery color with purple luster, complete absence of spots or pubescent lines on the elytra, and distinctive patches of white pubescence along the sides. These congeners develop only in dead wood and are generally smaller with different color patterns.

Relatively large for the genus Agrilus. Dorsal surface coppery with purple luster. Elytra lack spots or pubescent lines. Distinctive patches of white pubescence present along lateral portions of thorax and abdomen. Underside strongly bronzy green with prominent white densely pubescent patches. Legs more or less coppery.

Associated with honey locust trees (Gleditsia triacanthos), particularly in urban and landscape settings where trees may be stressed. Native populations occur in natural habitats where honey locust grows. Adults are found on foliage and branches of host trees.

North America. Present throughout the range of its host plant Gleditsia triacanthos, which is native to central North America. GBIF records indicate presence in the Nearctic region, with distribution centered in the United States.

Adult emergence begins as early as early June (5 June recorded in 1982) and continues through mid-July (22 July recorded in 1983). Adults are active during spring and early summer, with peak activity likely varying by latitude and local conditions.

• Gleditsia triacanthos - larval hostAlmost exclusive host; larvae mine beneath bark of living trees, damaging cambium layer

Larvae mine beneath the bark of living honey locust trees, feeding on the cambium layer and interfering with movement of water and nutrients. Development occurs in living wood rather than dead branches, distinguishing this species from most other Agrilus. Adults emerge through D-shaped exit holes in trunk and main branches.

Adults are difficult to detect visually on branches even when present in high numbers; beating branches onto a sheet is required for reliable detection. Under cool, moist, cloudy conditions adults are less active and easier to collect. Adults do not immediately fly when disturbed under such conditions. In sunny, warm conditions adults are highly active and quickly fly from beating sheets.

A pest species that exploits stressed or weakened honey locust trees. In natural settings likely plays a role in population dynamics of its host by attacking declining individuals. In urban landscapes, contributes to tree mortality when trees are planted in suboptimal sites or suffer from stress.

Significant pest of ornamental honey locust trees in urban landscapes, particularly thornless cultivars widely planted in the eastern United States. Infestations cause branch dieback, canopy thinning, and tree death in severe cases. D-shaped exit holes on trunk and branches are diagnostic of infestation. Chemical control is generally not feasible once infestation begins; prevention through proper site selection and tree care is recommended. Economic impact includes tree replacement costs and reduced aesthetic value of landscape plantings.

• Agrilus egeniformisAlso reared from honey locust, but develops only in dead wood; smaller size and different color pattern
• Agrilus fallaxAlso reared from honey locust, but develops only in dead wood; smaller size and different color pattern
• Agrilus pseudofallaxAlso reared from honey locust, but develops only in dead wood; smaller size and different color pattern

• pest
• urban entomology
• ornamental pest
• Buprestidae
• jewel beetle
• wood-borer

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
• Honey Locust Borer | Beetles In The Bush
• Buprestidae | Beetles In The Bush | Page 9
• jewel beetles | Beetles In The Bush | Page 8
• taxonomy | Beetles In The Bush | Page 4
• Two new species of Agrilus from Mexico | Beetles In The Bush
• Agrilus fuscipennis on Persimmon | Beetles In The Bush
• Emergence and Adult Biology of <i>Agrilus Difficilis</i> (Coleoptera: Buprestidae), a Pest of Honeylocust, <i>Gleditsia Triacanthos</i>